Family name Гаідайчук (Гаідайчук 
) , across the world, is an extremely rare last name. The last name Гаідайчук is habitual in Eastern Europe, particularly Ukraine, where it is an extremely rare surname.
| VARIANT | COUNTRY |
|---|---|
| Гаідайчук | Ukraine |
Gaidaichuk, and Haidaichuk